Answer
$l=\dfrac{8t^2}{\pi^2}$
Work Step by Step
Divide $2\pi$ on both sides to obtain:
$\dfrac{t}{2\pi}=\sqrt{\dfrac{l}{32}}$
Square both sides to obtain:
$\dfrac{t^2}{4\pi^2}=\dfrac{l}{32}$
Multiply $32$ on both sides to obtain:
$\require{cancel}
32 \cdot \dfrac{t^2}{4\pi^2} = \dfrac{lA}{32} \cdot 32
\\\dfrac{8\cancel{32}t^2}{\cancel{4}\pi^2} = \dfrac{l}{\cancel{32}} \cdot \cancel{32}
\\\dfrac{8t^2}{\pi^2} = l$
